A high-rigidity composite material thick plate and its preparation method

Abstract

A high-rigidity composite material thick plate and a preparation method thereof, comprising a plate core, with surface layers connected to the upper and lower surfaces of the plate core respectively. The material of the plate core is a thermoplastic resin foamed by a foaming agent. The surface layer includes an adhesive medium layer, a reinforcing layer and a protective layer. The reinforcing layer is connected to one surface of the adhesive medium layer, and the protective layer is connected to the surface of the reinforcing layer. The other surface of the adhesive medium layer is compounded with the corresponding surface of the plate core into one body. The reinforcing layer is formed by laying single-layer or multi-layer continuous fiber reinforced thermoplastic resin prepreg sheets. The material of the adhesive medium layer is a porous breathable material. One surface of the adhesive medium layer facing the reinforcing layer partially embeds into the continuous fiber reinforced thermoplastic resin prepreg sheets in the reinforcing layer, and one surface of the adhesive medium layer facing the plate core partially embeds into the plate core. This high-rigidity composite material thick plate not only maintains the advantages of high strength, high impact resistance and light weight, but also has high rigidity, high peel strength, high nail-holding force and high processing efficiency.

Description

Technical Field

[0001] The invention relates to a high-rigidity composite material thick plate and a preparation method thereof. Background Art

[0002] Thermoplastic composite panels have a wide range of applications due to their light weight and high strength. Take the transportation industry as an example. For new energy trucks, the lightweight and high-strength thermoplastic composite panel can greatly extend the endurance of new energy trucks and the impact resistance of the compartment. At present, the compartment panels of trucks often use thermoplastic composite honeycomb panels. Although the modulus of thermoplastic composite honeycomb panels is relatively high, due to the characteristics of the loose pore structure of the honeycomb core, although the weight of the panel can be greatly reduced, when installing components, such as installing metal stress-bearing structural parts such as frames, profiles, locks, handles, etc., the stress-bearing connection points are prone to dents, leaks, and low holding force. Especially for the door panels of the compartment, due to their low holding force, light panels, and insufficient thickness, they are insufficiently rigid. Therefore, when the door panels are frequently opened and closed and collided, it is easy for their metal parts to fall off, the connection holes to expand, and the door panels to become loose.

[0003] Chinese Patent 201610103703.6 discloses a fiber-reinforced building formwork and a preparation method thereof, wherein the fiber-reinforced building formwork comprises a wooden board core, wherein the upper and lower surfaces of the board core are respectively connected with a surface layer formed by a composite of continuous fiber-reinforced thermoplastic prepreg sheets, wherein the surface layer and the board core are further connected as a whole through an adhesive layer, wherein the adhesive layer is a non-woven fabric, and the surface layer, the board core and the adhesive layer are composited as a whole through hot pressing. Although this fiber-reinforced building formwork has the advantages of higher static bending strength, static bending modulus and light weight, because it adopts a wooden board core, when this formwork is applied in the transportation industry, it is easy to cause the wooden board core to absorb more moisture due to being placed in an environment exposed to the sun and rain, thereby causing a significant decrease in the overall bending strength of the formwork and the peeling strength of the surface layer, and also causing a significant decrease in the nail holding force of the formwork, resulting in installation. The metal parts thereon are easy to fall off; according to the description of the preparation method in the public document, the preparation of the board core, the preparation of the surface layer and the composite of the board core and the surface layer are carried out separately, the processing process is discontinuous, and manual intervention is required, so the processing efficiency is low and it is not suitable for mass production; in addition, because the composite of the surface layer, the adhesive layer and the board core adopts traditional hot pressing direct composite molding, the connection between the adhesive layer and the surface layer and the board core is only surface-to-surface bonding. For thick plates that require high rigidity, the surface layer and the board core are easy to delaminate and peel off during long-term use, and the peeling strength is low. Therefore, the preparation method in the above-mentioned public document is not suitable for the preparation of plates with larger thickness and higher rigidity requirements; in addition, because a large amount of adhesive is required in the preparation of the board core in the above-mentioned public document, the finished board has a strong odor and is not environmentally friendly. Summary of the invention

[0004] The present invention aims to provide a high-rigidity composite material thick plate with low water absorption rate and capable of maintaining high flexural strength, high peel strength, and high nail-holding force after water absorption, as well as a preparation method for the high-rigidity composite material thick plate with high processing efficiency.

[0005] A high-rigidity composite material thick plate according to the present invention includes a plate core, and surface layers are respectively connected to the upper and lower surfaces of the plate core. The material of the plate core is a thermoplastic resin foamed and formed by a foaming agent. The surface layer includes an adhesive medium layer, a reinforcing layer, and a protective layer. The reinforcing layer is connected to one surface of the adhesive medium layer, and the protective layer is connected to the surface of the reinforcing layer. The other surface of the adhesive medium layer is compounded with the corresponding surface of the plate core as a whole. The reinforcing layer is formed by laying single-layer or multi-layer continuous fiber reinforced thermoplastic resin prepreg sheets. The material of the adhesive medium layer is a porous breathable material. A part of the surface of the adhesive medium layer facing the reinforcing layer is embedded in the continuous fiber reinforced thermoplastic resin prepreg sheets in the reinforcing layer, and a part of the surface of the adhesive medium layer facing the plate core is embedded in the plate core.

[0006] A preparation method for a high-rigidity composite material thick plate according to the present invention comprises the following steps:

[0007] 1) Preparation of the surface layer: Lay the protective layer, the reinforcing layer, and the adhesive medium layer in sequence from top to bottom. When the reinforcing layer is composed of multi-layer continuous fiber reinforced thermoplastic resin prepreg sheets, the multi-layer continuous fiber reinforced thermoplastic resin prepreg sheets are laid in sequence from top to bottom. Place the protective layer, the reinforcing layer, and the adhesive medium layer laid in sequence as a whole into a hot press for hot pressing and compounding to form the surface layer, and then wind it up for standby. The plane gap of the hot press is consistent with the thickness of the surface layer, and the continuous production speed of the surface layer is 1.5 m / min to 12 m / min.

[0008] 2) Preparation of the plate core: Add the thermoplastic resin added with a foaming agent into a screw extruder. The screw extruder extrudes the thermoplastic resin into the heating die cavity for forming the plate core. As the screw extruder continuously operates, the formed plate core is pushed out of the heating die cavity. The gap of the heating die cavity is consistent with the thickness of the plate core, and the heating temperature of the heating die cavity is lower than the heating temperature of the screw extruder. The continuous production speed of the plate core is 0.5 m / min to 3 m / min.

[0009] 3) Preparation of thick plates: After heating the mold cavity, a pair of heating rollers arranged vertically are provided. Feeding rollers are respectively provided above the upper heating roller and below the lower heating roller. The wound surface layers are placed on the feeding rollers. The starting ends of the wound surface layers are pulled out and wound around the corresponding heating rollers. The plate cores sent out from the heating mold cavity directly enter between the two heating rollers. At the same time, the two heating rollers rotate to make the surface layers wound on them composite on the corresponding surfaces of the plate cores, forming thick plates. With the continuous extrusion of the screw extruder, the thick plates continue to move forward into the cooling and shaping mold cavity for cooling. Finally, with the continuous extrusion of the screw extruder, the thick plates in the cooling and shaping mold cavity are sent out of the cooling and shaping mold cavity and then cut. The gap between the two heating rollers is consistent with the thickness of the thick plates;

[0010] 4) After all the thermoplastic resin in the screw extruder is completely extruded, the screw extruder stops running, completing the continuous processing of all thick plates.

[0011] The high-rigidity composite material thick plate and its preparation method described in the present invention can continuously process the thick plate without manual intervention due to the synergistic effect of continuous extrusion of the screw extruder and the heating cavity, heating roller and cooling and shaping cavity, so that the processing of the thick plate can be carried out without manual intervention, and the processing efficiency is high, which is suitable for mass production. When preparing the thick plate, the surface layer is rolled and laid on the surface of the plate core by two heating rollers, so that the delamination phenomenon caused by the use of traditional hot pressing composite materials at this stage due to the excessive thickness of the plate (such as 8mm~200mm thick plate) can be effectively solved, and the high rigidity of the thick plate is effectively guaranteed. As the core of the board, its water absorption rate is very low. Therefore, it can not only keep the thick board lightweight, but also make this hard solid thick board have higher rigidity to ensure the connection of metal parts, ensure a higher nail holding force, and avoid the falling off of metal parts. In addition, by combining the hard solid core with the surface layer containing continuous fiber reinforced thermoplastic resin prepreg sheet layer, it can still ensure that the thick board has high strength, high modulus and high impact resistance; since the processing speed of the surface layer is 1.5m / min~12m / min, the processing speed of forming the core is 0.5m / min~3m / min, so it can ensure that the surface layer The thermoplastic resin in the continuous fiber reinforced thermoplastic resin prepreg sheet layer and the upper and lower surfaces of the board core between the two heating rollers can be melted, so that the thermoplastic resin can fully penetrate into the adhesive medium layer made of porous breathable material, so that the adhesive medium layer is partially embedded in the continuous fiber reinforced thermoplastic resin prepreg sheet layer on the corresponding surface and partially embedded in the board core on the corresponding surface. After cooling, the adhesive medium layer will form an interlaced overlapping structure with the continuous fiber reinforced thermoplastic resin prepreg sheet layer and the board core to achieve physical and mechanical locking, which is much stronger than the strength of bonding by molecular force, thereby making the bonding strength between the surface layer and the board core stronger. The degree is greatly improved, and the peel strength between the surface layer and the core of the board is greatly enhanced. Combined with the high rigidity of the thick plate, it is sufficient to effectively avoid the delamination phenomenon inside the surface layer and between the surface layer and the core of the board. At the same time, due to the above-mentioned surface layer processing speed, it can effectively avoid the adhesive medium layer from being embedded in the continuous fiber reinforced thermoplastic resin prepreg sheet layer too much, and prevent the adhesive medium layer from being exposed to the continuous fiber reinforced thermoplastic resin prepreg sheet layer after hot pressing, which cannot be effectively connected with the core of the board later. In addition, since the use of adhesives for connection is abandoned in the production of the core and the surface layer, the molded board has less odor and is more environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the structure of the high-rigidity composite material thick plate of the present invention.

[0013] Figure 2 It is a processing flow chart of the present invention. DETAILED DESCRIPTION

[0014] A high rigidity composite material thick plate, such as Figure 1and Figure 2 As shown in Figure 2 , it includes a board core 1, with surface layers connected to the upper and lower surfaces of the board core 1 respectively. The material of the board core 1 is a thermoplastic resin foamed by a foaming agent. The surface layer includes an adhesive medium layer 2, a reinforcing layer 3, and a protective layer 4. The reinforcing layer 3 is connected to one surface of the adhesive medium layer 2, and the protective layer 4 is connected to the surface of the reinforcing layer 3. The other side of the adhesive medium layer 2 is compounded with the corresponding surface of the board core 1 as a whole. The reinforcing layer 3 is formed by laying single-layer or multi-layer continuous fiber reinforced thermoplastic resin prepreg sheets. The material of the adhesive medium layer 2 is a porous breathable material. One side of the adhesive medium layer 2 facing the reinforcing layer 3 is partially embedded in the continuous fiber reinforced thermoplastic resin prepreg sheets in the reinforcing layer 3, and one side of the adhesive medium layer 2 facing the board core is partially embedded in the board core 1.

[0015] The protective layer 4 is a thin film, composite film, or composite base fabric, etc. The material of the protective layer 4 is selected from one or a combination of EVA, PE, PP, PET, PA, and aluminum foil, which can endow the formed board with excellent properties such as high anti-aging property, wear resistance, heat resistance, and corrosion resistance, and greatly extend the service life of the board.

[0016] The thickness of the reinforcing layer 3 is 0.3 mm to 1 mm, such as 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, or 1.0 mm, etc., and the areal density is 150 g / m² to 1500 g / m 2 , such as 150 g / m 2 、200 g / m 2 、250 g / m 2 、300 g / m 2 、350 g / m 2 、400 g / m 2 、450 g / m 2 、500 g / m 2 、550 g / m 2 、600 g / m 2 、650 g / m 2 、700 g / m 2 、750 g / m 2 、800 g / m 2 、850 g / m 2 、900 g / m 2 、950 g / m 2 、1000 g / m 2 、1100 g / m 2 、1200 g / m 2 、1300 g / m 2 、1400 g / m 2or 1500 g / m 2 etc.

[0017] The reinforcing layer 3 is composed of two to four layers of continuous fiber reinforced thermoplastic resin prepreg sheets laminated together. The continuous fiber reinforced thermoplastic resin prepreg sheet is composed of unidirectional continuous fibers and a thermoplastic resin matrix. When the reinforcing layer 3 is composed of multiple layers of continuous fiber reinforced thermoplastic resin prepreg sheets laminated together, the laying angles of adjacent continuous fiber reinforced thermoplastic resin prepreg sheets are different. When the reinforcing layer 3 is composed of two layers of continuous fiber reinforced thermoplastic resin prepreg sheets laminated together, the laying angles are 0° / 90° or 90° / 0°, etc. When the reinforcing layer 3 is composed of three layers of continuous fiber reinforced thermoplastic resin prepreg sheets laminated together, the laying angles are 0° / 90° / 0° or 90° / 0° / 90°, etc. When the reinforcing layer 3 is composed of four layers of continuous fiber reinforced thermoplastic resin prepreg sheets laminated together, the laying angles are 0° / 90° / 90° / 0° or 90° / 0° / 0° / 90°, etc. In actual production, it is not limited to the above laying angles. The laying angles of adjacent continuous fiber reinforced thermoplastic resin prepreg sheets are set according to actual needs, as long as the laying angles of the symmetric layers are the same to ensure the strength in the same direction. Based on the total weight of a single layer of continuous fiber reinforced thermoplastic resin prepreg sheet, the weight percentage of continuous fibers is 40wt% - 80wt%, such as 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, etc., preferably 55wt% - 65wt%. The weight percentage of the thermoplastic resin matrix is 20wt% - 60wt%, such as 20 wt%, 30 wt%, 35wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, etc., preferably 35wt% - 45wt%.

[0018] The material of the continuous fiber is selected from one or more combinations of glass fiber, carbon fiber, aramid fiber, basalt fiber, and silicon carbide fiber. The diameter of the continuous fiber is 5μm - 20μm, such as 5μm, 8μm, 10μm, 14μm, 16μm, 18μm, 20μm, etc. The thermoplastic resin matrix is selected from one or more combinations of polyethylene, polypropylene, polyamide, recycled polyethylene, recycled polypropylene, and recycled polyamide.

[0019] The adhesive medium layer 2 is non-woven fabric or cotton paper, etc. The material of the non-woven fabric is selected from one or more combinations of PET, PA, and viscose fiber. The type of the non-woven fabric is needle-punched non-woven fabric, spunlace non-woven fabric, or hot-rolled spunbond non-woven fabric. The areal density of the adhesive medium layer is 30 g / m 2 <α ≤ 50 g / m 2 , such as 30 g / m2 , 31 g / m 2 , 35 g / m 2 , 37 g / m 2 , 40 g / m 2 , 42 g / m 2 , 44 g / m 2 , 47 g / m 2 , 48 g / m 2 or 50 g / m 2 , etc., preferably α = 40 g / m 2 . Within this range of areal density, the number of pore structures in the adhesive medium layer is appropriate, which can enable the adhesive medium layer 2 to have an effective embedding depth with the continuous fiber reinforced thermoplastic resin prepreg sheet layer and the board core 1, ensuring a more reliable connection between the adhesive medium layer 2 and the two. Once the areal density of the adhesive medium layer 2 is less than or greater than the above range, the peel strength will decrease significantly.

[0020] The material of the board core 1 is selected from one or a combination of polyethylene, recycled polyethylene, polyethylene composite material, polypropylene, recycled polypropylene, and polypropylene composite material; the bulk density of the board core is 0.4 g / cm3 to 1.2 g / cm3, such as 0.4 g / cm3, 0.5 g / cm3, 0.6 g / cm3, 0.7 g / cm3, 0.8 g / cm3, 0.9 g / cm3, 1 g / cm3, 1.1 g / cm3, 1.2 g / cm3, etc., which not only makes the board core 1 have a lighter mass but also effectively ensures the rigidity and nail holding force of the thick board formed by the board core 1.

[0021] The blowing agent is an azo compound (such as azodicarbonamide, azobisisobutyronitrile, barium azodicarboxylate), an N-nitroso compound (such as N, N'-dicyclonitrosopentamethylenetetramine), or a hydrazide compound, etc.; the blowing aid is selected from one or a combination of alkali metal oxides (such as zinc oxide), organic acids or inorganic acid salts (such as cadmium stearate), polyols, and organosilicon compounds.

[0022] The melting point of the adhesive medium layer 2 ≥ the melting point of the thermoplastic resin matrix in the reinforcing layer 3 ≥ the melting point of the thermoplastic resin in the board core 1, to avoid damaging the adhesive medium layer during heating.

[0023] A method for preparing a thick plate of a high-rigidity composite material comprises the following steps: (1) Preparation of the surface layer: Lay the protective layer 4, the reinforcing layer 3, and the adhesive medium layer 2 in sequence from top to bottom. When the reinforcing layer 3 is composed of multiple layers of continuous fiber-reinforced thermoplastic resin prepreg sheets, the multiple layers of continuous fiber-reinforced thermoplastic resin prepreg sheets are laid in sequence from top to bottom. Place the protective layer 4, the reinforcing layer 3, and the adhesive medium layer 2 laid in sequence as a whole into a hot press for hot pressing and compounding to form the surface layer, and then wind it up for standby. The planar gap of the hot press is consistent with the thickness of the surface layer. The hot pressing temperature is 180°C to 260°C, such as 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, etc. The pressure is 2 bar to 6 bar, such as 2 bar, 3 bar, 4 bar, 5 bar, 6 bar, etc. The continuous production speed of the surface layer is 1.5 m / min to 12 m / min, such as 1.5 m / min, 2 m / min, 2.5 m / min, 3 m / min, 3.5 m / min, 4 m / min, 4.5 m / min, 5 m / min, 5.5 m / min, 6 m / min, 6.5 m / min, 7 m / min, 7.5 m / min, 8 m / min, 8.5 m / min, 9 m / min, 9.5 m / min, 10 m / min, 10.5 m / min, 11 m / min, 11.5 m / min, 12 m / min, etc. (2) Preparation of the core board 1: Add the thermoplastic resin added with a foaming agent into the screw extruder 5. The screw extruder 5 extrudes the thermoplastic resin into the heating die cavity 6 for forming the core board 1. As the screw extruder 5 continuously operates, it pushes the formed core board 1 out of the heating die cavity 6. The gap of the heating die cavity 6 is consistent with the thickness of the core board 1. The heating temperature of the screw extruder 5 is 180°C to 280°C, such as 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, or 280°C, etc. The heating temperature of the heating die cavity 6 is 200°C to 300°C, such as 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C, or 300°C, etc. The heating temperature of the heating die cavity 6 should be higher than the heating temperature of the screw extruder 5. The continuous production speed of the core board is 0.5 m / min to 3 m / min, such as 0.5 m / min, 0.8 m / min, 1 m / min, 1.3 m / min, 1.5 m / min, 1.7 m / min, 1.9 m / min, 2 m / min, 2.2 m / min, 2.5 m / min, 2.7 m / min, 2.9 m / min, 3 m / min, etc.; (3) Preparation of thick plates: After the heating die cavity 6, there is a pair of heating rollers 7 arranged vertically. Above the upper heating roller 7 and below the lower heating roller 7, feeding rollers 8 are respectively arranged. The rolled surface layer is placed on the feeding rollers 8. The starting end of the rolled surface layer is pulled out and wound around the corresponding heating roller 7. The plate core 1 sent out from the heating die cavity 6 directly enters between the two heating rollers 7. At the same time, the two heating rollers 7 rotate to make the surface layer wound on them composite on the corresponding surface of the plate core 1 to form a thick plate. With the continuous extrusion of the screw extruder 5, the thick plate continues to move forward into the cooling and shaping die cavity 9 for cooling. Finally, with the continuous extrusion of the screw extruder 5, the thick plate in the cooling and shaping die cavity 9 is sent out of the cooling and shaping die cavity 9 and then cut. The temperature of the heating rollers 7 is 150°C to 250°C, such as 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C or 250°C, etc. The gap between the two heating rollers 7 is the same as the thickness of the thick plate. The composite pressure between the two heating rollers 7 is 3 bar to 6 bar, such as 3 bar, 3.5 bar, 4 bar, 4.5 bar, 5 bar, 5.5 bar, 6 bar, etc.; (4) Until all the thermoplastic resin in the screw extruder 5 is completely extruded, the screw extruder 5 stops running, and the continuous processing of all thick plates is completed. Among them, the screw extruder 5, the heating rollers 7, the heating die cavity 6 and the cooling and shaping die cavity 9 are all prior arts.

[0024] In step (3), when the thick plate is cooled in the cooling and shaping die cavity 9, it needs to be cooled in three stages. The cooling temperature of the first stage is 50°C to 80°C, such as 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, etc. The cooling temperature of the second stage is 20°C to 50°C, such as 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, etc. The cooling temperature of the third stage is 10°C to 20°C, such as 10°C, 15°C, 20°C, etc. Then the thick plate is sent out from the cooling and shaping die cavity 9. Through segmented cooling, the crystal grains inside the plate can be refined, effectively enhancing the strength of the plate.

[0025] The cooling gap of the cooling and shaping die cavity 9 ≤ the gap between the two heating rollers 7. Since the size of the thick plate will shrink correspondingly after coming out from between the two heating rollers 7 and entering the cooling and shaping die cavity 9 for cooling, therefore, the cooling gap of the cooling and shaping die cavity 9 ≤ the gap between the two heating rollers 7 can effectively shape the thick plate.

[0026] The directional indications (such as the upper surface, the lower surface, etc.) involved in the present invention are only used to explain the relative position relationship between the components when the composite material compartment panel is in a state such as Figure 1 When this specific state changes, the directional indication also changes accordingly.

[0027] The present invention will be further described below through specific embodiments. The following embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the following embodiments.

[0028] Embodiment 1

[0029] The material of the core board 1 is polyethylene, the foaming agent is azodicarbonamide, the foaming aid is zinc oxide, the volume density of the core board is 0.4 g / cm3, the protective layer 4 in the surface layer is a polyethylene film, the thickness of the reinforcing layer 3 is 0.6 mm, and the areal density of the reinforcing layer 3 is 900 g / m2. It is composed of two layers of unidirectional continuous glass fiber reinforced thermoplastic resin prepreg sheets laminated together. The laying angle of adjacent continuous glass fiber reinforced thermoplastic resin prepreg sheets is 0° / 90°. The continuous glass fiber reinforced thermoplastic resin prepreg sheet is composed of unidirectional continuous glass fiber and polyethylene. Based on the total weight of a single layer of continuous glass fiber reinforced thermoplastic resin prepreg sheet, the weight percentage of continuous glass fiber is 60 wt%, the diameter of continuous glass fiber is 10 μm, and the weight percentage of the thermoplastic resin matrix is 40 wt%. The adhesive medium layer 2 is a PET hot-rolled spunbond non-woven fabric with an areal density of 31 g / m2. The thick board is prepared by the above method for preparing a high-rigidity composite material thick board. Among them, the hot pressing temperature during the preparation of the surface layer is 200 °C, the hot pressing pressure is 2 bar, and the processing speed is 8 m / min. When preparing the core board, the temperature of the screw extruder 5 is 200 °C, the heating temperature of the heating die cavity 6 is 250 °C, and the processing speed for continuously producing the core board is 2 m / min. The temperature of the heating roller 7 during the preparation of the thick board is 200 °C, and the composite pressure between the two heating rollers 7 is 3 bar. The first-stage cooling temperature of the thick board in the cooling and shaping die cavity 9 is 60 °C, the second-stage cooling temperature is 40 °C, and the third-stage cooling temperature is 20 °C.

[0030] According to GB / T17657-2013, the flexural strength, nail holding force, peel strength of the surface layer, and water absorption rate of the thick board before water absorption are tested as follows: the flexural strength is 27 MPa, the peel strength of the surface layer is 125 N / mm, the nail holding force is 3800 N, and the water absorption rate is 1%. After impregnation for 24 h, the flexural strength decreases by 0.8%, the peel strength of the surface layer decreases by 7%, and the nail holding force decreases by 0.5%.

[0031] Comparative Example 1

[0032] Peeled veneer is dried at 60°C to 110°C for 4h to 8h. Glue is applied to the veneer. After applying the glue, multiple layers of veneer are laid together so that the directions of the wood fibers of adjacent veneers are perpendicular to each other to form a board core. Subsequently, the board core is cold-pressed at a pressure of 8MPa to 20MPa for 30min to 2h, and then hot-pressed and cured at a temperature of 70°C to 140°C and a hot-pressing pressure of 8MPa to 20MPa for 8min to 15min to obtain the board core; Two layers of continuous glass fiber-reinforced thermoplastic resin prepreg sheets are laid at 0° / 90° and hot-pressed and compounded. The continuous glass fiber-reinforced thermoplastic resin prepreg sheet layer is composed of unidirectional continuous glass fibers and polyethylene. The hot-pressing temperature is 200°C and the hot-pressing pressure is 2 bar to obtain the surface layer. The thickness of the two layers of continuous glass fiber-reinforced thermoplastic resin prepreg sheets is 0.6mm. The surface density of the surface layer made of two layers of continuous glass fiber-reinforced thermoplastic resin prepreg sheets is 900g / m2. Based on the total weight of the single-layer continuous glass fiber-reinforced thermoplastic resin prepreg sheet layer, the weight percentage of continuous glass fibers is 60wt% and the weight percentage of the thermoplastic resin matrix is 40wt%; A layer of PET hot-rolled spunbond non-woven fabric is compounded on one side of the surface layer as an adhesive medium layer. The surface density of the PET hot-rolled spunbond non-woven fabric is 31 g / m2. The side of the surface layer with the PET hot-rolled spunbond non-woven fabric is hot-pressed and compounded with the upper and lower surfaces of the board core by a hot press to form a template.

[0033] According to GB / T17657-2013, the flexural strength, nail-holding force before the thick board absorbs water, the peel strength of the surface layer, and the water absorption rate are tested as follows: the flexural strength is 20MPa, the peel strength of the surface layer is 80N / mm, the nail-holding force is 3000N, and the water absorption rate is 31%; After soaking for 24h, the flexural strength decreases by 52%, the peel strength of the surface layer decreases by 23%, and the nail-holding force decreases by 18%.

[0034] It can be seen that on the premise of maintaining the advantages of light weight, high strength, and good impact resistance, the thick board in Example 1 has a low water absorption rate and can still maintain high rigidity after absorbing water. The nail-holding force, peel strength, and flexural strength are all better than those of the template in Comparative Example 1, and it is more suitable for the transportation industry.

[0035] Example 2

[0036] The surface density of the PET hot-rolled spunbond non-woven fabric is set to 40 g / m2, and the rest is the same as in Example 1. According to GB / T17657-2013, the flexural strength, nail-holding force before the thick board absorbs water, the peel strength of the surface layer, and the water absorption rate are tested as follows: the flexural strength is 30MPa, the peel strength of the surface layer is 160N / mm, the nail-holding force is 3800N, and the water absorption rate is 1.1%; After soaking for 24h, the flexural strength decreases by 0.7%, the peel strength of the surface layer decreases by 6%, and the nail-holding force decreases by 0.5%.

[0037] Example 3

[0038] The surface density of the PET hot-rolled spunbond non-woven fabric is set to 40 g / m2, and the volume density of the board core is 1 g / cm3. The rest of the content is the same as that of Example 1. According to GB / T17657-2013, the flexural strength, nail-holding force, peel strength of the surface layer, and water absorption rate of the thick board before water absorption are tested as follows: the flexural strength is 35 MPa, the peel strength of the surface layer is 170 N / mm, the nail-holding force is 4000 N, and the water absorption rate is 0.7%; after 24 hours of impregnation, the flexural strength decreases by 0.5%, the peel strength of the surface layer decreases by 4%, and the nail-holding force decreases by 0.3%.

[0039] Example 4

[0040] The surface density of the PET hot-rolled spunbond non-woven fabric is set to 40 g / m2, and the volume density of the board core is 1.2 g / cm3. The rest of the content is the same as that of Example 1. According to GB / T17657-2013, the flexural strength, nail-holding force, peel strength of the surface layer, and water absorption rate of the thick board before water absorption are tested as follows: the flexural strength is 37 MPa, the peel strength of the surface layer is 180 N / mm, the nail-holding force is 4200 N, and the water absorption rate is 0.6%; after 24 hours of impregnation, the flexural strength decreases by 0.5%, the peel strength of the surface layer decreases by 3%, and the nail-holding force decreases by 0.3%.

Claims

1. A thick plate of a high-rigidity composite material, comprising a plate core (1), and surface layers are respectively connected to the upper and lower surfaces of the plate core (1), and it is characterized in that: The material of the board core (1) is a thermoplastic resin foamed by a foaming agent. The surface layer includes an adhesive medium layer (2), a reinforcing layer (3), and a protective layer (4). The reinforcing layer (3) is connected to one surface of the adhesive medium layer (2), and the protective layer (4) is connected to the surface of the reinforcing layer (3). The other surface of the adhesive medium layer (2) is compounded with the corresponding surface of the board core (1) into one body. The reinforcing layer (3) is formed by laying single-layer or multi-layer continuous fiber reinforced thermoplastic resin prepreg sheets. The material of the adhesive medium layer (2) is a porous breathable material. One surface of the adhesive medium layer (2) facing the reinforcing layer (3) is partially embedded in the continuous fiber reinforced thermoplastic resin prepreg sheets in the reinforcing layer (3), and one surface of the adhesive medium layer (2) facing the board core (1) is partially embedded in the board core (1); The thermoplastic resin is selected from one or more combinations of polyethylene, polypropylene, and polyamide. The adhesive medium layer (2) is a non-woven fabric. The material of the non-woven fabric is selected from one or more combinations of PET and PA. The melting point of the adhesive medium layer (2) > the melting point of the thermoplastic resin in the reinforcing layer (3) > the melting point of the thermoplastic resin in the board core (1). The type of non-woven fabric is needle-punched non-woven fabric, spunlaced non-woven fabric, or heat-bonded spunbond non-woven fabric; The surface density of the adhesive medium layer (2) is 30 g / m 2 <α ≤ 50 g / m 2 .

2. The high-rigidity composite material thick plate according to claim 1, wherein: The protective layer (4) is a thin film, composite film or composite base fabric, and the material of the protective layer (4) is selected from one or more combinations of EVA, PE, PP, PET, PA, and aluminum foil.

3. The high-rigidity composite material thick plate according to claim 1, wherein: The thickness of the reinforcing layer (3) is 0.3 mm to 1 mm, and the areal density is 150 g / m 2 ~ 1500 g / m 2 .

4. A high-rigidity composite material thick plate according to claim 3, characterized in that: The reinforcing layer (3) is composed of two to four layers of continuously fiber-reinforced thermoplastic resin prepreg sheets laminated together. The continuously fiber-reinforced thermoplastic resin prepreg sheet is composed of unidirectional continuous fibers and a thermoplastic resin. When the reinforcing layer (3) is composed of multiple layers of continuously fiber-reinforced thermoplastic resin prepreg sheets, the laying angles of adjacent continuously fiber-reinforced thermoplastic resin prepreg sheets are different; based on the total weight of a single layer of continuously fiber-reinforced thermoplastic resin prepreg sheet, the weight percentage of the continuous fibers is 40wt% - 80wt%, and the weight percentage of the thermoplastic resin is 20wt% - 60wt%; the material of the continuous fibers is selected from one or more combinations of glass fibers, carbon fibers, aramid fibers, basalt fibers, and silicon carbide fibers, and the diameter of the continuous fibers is 5μm - 20μm.

5. The high-rigidity composite material thick plate according to claim 4, wherein: The areal density of the adhesive medium layer (2) is α = 40 g / m 2 .

6. The high-rigidity composite material thick plate according to claim 1, characterized in that: The bulk density of the board core (1) is 0.4 g / cm 3 ~1.2 g / cm 3 .

7. A thick plate of a high-rigidity composite material according to claim 1, characterized in that: The blowing agent is an azo compound blowing agent, an N-nitroso compound blowing agent, or a hydrazide compound blowing agent; the blowing aid is selected from one or more combinations of alkali metal oxide blowing aids, organic acid or inorganic acid salt blowing aids, polyol blowing aids, and silicone compound blowing aids.

8. A method for preparing a high-rigidity composite material thick plate as described in claim 1, characterized in that, The steps are as follows: 1) Preparation of the surface layer: Lay the protective layer (4), the reinforcing layer (3), and the adhesive medium layer (2) in sequence from top to bottom. When the reinforcing layer (3) is composed of multiple layers of continuously fiber-reinforced thermoplastic resin prepreg sheets, the multiple layers of continuously fiber-reinforced thermoplastic resin prepreg sheets are laid in sequence from top to bottom; put the protective layer (4), the reinforcing layer (3), and the adhesive medium layer (2) laid together in sequence into a hot press for hot pressing and laminating to form the surface layer, and then wind it up for standby; the flat gap of the hot press is consistent with the thickness of the surface layer, and the continuous production speed of the surface layer is 1.5m / min - 12m / min; 2) Preparation of the board core (1): Add the thermoplastic resin added with the blowing agent into the screw extruder (5), and the screw extruder (5) extrudes the thermoplastic resin into the heating die cavity (6) of the formed board core (1). As the screw extruder (5) continuously operates, push the formed board core (1) out of the heating die cavity (6). The gap of the heating die cavity (6) is consistent with the thickness of the board core (1), and the heating temperature of the heating die cavity (6) is higher than the heating temperature of the screw extruder (5). The continuous production speed of the board core is 0.5m / min - 3m / min; 3) Preparation of thick plate: A pair of heating rollers (7) arranged vertically are provided behind the heating die cavity (6). Feeding rollers (8) are respectively provided above the upper heating roller (7) and below the lower heating roller (7). The wound surface layer is placed on the feeding rollers (8). The starting end of the wound surface layer is pulled out and wound around the corresponding heating roller (7). The plate core (1) sent out from the heating die cavity (6) directly enters between the two heating rollers (7). At the same time, the two heating rollers (7) rotate to make the surface layer wound on them composite on the corresponding surface of the plate core (1) to form a thick plate. With the continuous extrusion of the screw extruder (5), the thick plate continues to move forward into the cooling and shaping die cavity (9) for cooling. Finally, with the continuous extrusion of the screw extruder (5), the thick plate in the cooling and shaping die cavity (9) is sent out of the cooling and shaping die cavity (9) and then cut. The gap between the two heating rollers (7) is consistent with the thickness of the thick plate; 4) After all the thermoplastic resin in the screw extruder (5) is completely extruded, the screw extruder (5) stops running, and the continuous processing of all thick plates is completed.

9. The preparation method of a high-rigidity composite material thick plate according to claim 8, characterized in that: In step 1), the hot pressing temperature is 180°C to 260°C, and the pressure is 2 bar to 6 bar; in step 2), the heating temperature of the screw extruder (5) is 180°C to 280°C, and the heating temperature of the heating die cavity (6) is 200°C to 300°C; in step 3), the temperature of the heating rollers (7) is 150°C to 250°C, and the composite pressure between the two heating rollers (7) is 3 bar to 6 bar.

10. The preparation method of a high-rigidity composite material thick plate according to claim 8 or 9, characterized in that: In step 3), when the thick plate is cooled in the cooling and shaping die cavity (9), it needs to be cooled in three stages. The first-stage cooling temperature is 50°C to 80°C, the second-stage cooling temperature is 20°C to 50°C, and the third-stage cooling temperature is 10°C to 20°C. Then the thick plate is sent out from the cooling and shaping die cavity (9).

11. The preparation method of a high-rigidity composite material thick plate according to claim 8, characterized in that: The cooling gap of the cooling and shaping die cavity (9) ≤ the gap between the two heating rollers (7).

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